Pulsed repeater amplifier

ABSTRACT

1. A pulsed repeater amplifier circuit comprising three traveling wave tubes, each said tube having a helical coil disposed therewithin; an input antenna; an output antenna; means connecting the said antennas and the said tubes in cascade so that a wave received on the input antenna is conducted successively through the said three tubes to the output antenna; means for directing an electron beam of predetermined amplitude along the axis of the helical coil of each tube; and means responsive to an individual periodic high voltage energization cycle for each coil for amplifying the wave during separate intervlas as it travels through each tube.

United States Patent 91 Greene June 19, 1973 PULSED REPEATER AMPLIFIER Prima ExaminerBen'amin A. Borchelt 5 r t: kC.G ,s t,N.Y. J [7 1 nven or Jae teem yosse Assistant Examinerl-l. A. Birmiel [73] Assignee: The Unit d tat s f Am a 8 Att0rnpyArthur W. Collins and W, O. Quesenberry represented by the Secretary of the Navy, Washington, D.C.

Filed: Apr. 29, 1959 Appl. No.2 809,894

[52] U.S. Cl. 325/6, 325/120, 330/43,

315/393 [51] Int. Cl. 1104b 7/14 [58] Field of Search 330/43, 44, 150,

[56] References Cited UNITED STATES PATENTS 2,612,633 9/1952 Cutler 332/7 2,770,722 11/1956 Arams 250/15 X 2,849,545 8/1958 Mendel 330/43 EXEMPLARY CLAIM- A pulsed repeater amplifier circuit comprising three traveling wave tubes, each said tube having a helical coil disposed therewithin; an input antenna; an output antenna; means connecting the said antennas and the said tubes in cascade so thata wave received on the input antenna is conducted successively through the said three tubes to the output antenna; means for directing an electron beam of predetermined amplitude along the axis of the helical coil of each tube; and means responsive to an individual periodic high voltage energization cycle for each coil for amplifying the wave during separate intervlas as it travels through each tube.

3 Claims, 2 Drawing Figures MODULATOR -i DELAY-LINE PULSEI) REPEATER AMPLIFIER The present invention relates to pulsed radiofrequency amplifiers and more particularly to pulsed radio-frequency amplifiers which utilize cascaded traveling-wave tubes.

In conventional repeater jammer circuits the dual antenna pulsed repeater amplifier, wherein high gain is required and wherein the signal must be delayed for an appreciable interval before it is relayed, is oftentimes found particularly useful. One frequent objection to the use of the dual antenna amplifier, however, involves the degree of coupling between the input and output antennas. Even though these two antennas may be well shielded and isolated from one another, it is often difficult to obtain suitable attenuation between them to prevent feedback through the amplifier and avoid sustained oscillations therein.

Accordingly, it is a principal object of the present invention to provide a high gain dual antenna pulsed amplifier which will not break into oscillation.

It is a further object of the present invention to providea novel and improved dual antenna pulsed amplifier which includes a plurality of traveling wave tubes arranged in cascade wherein the interval between the time that one tube is pulsed on and the time the next tube is pulsed on is equal to the time delay of the signal in passing through the said one tube.

It is a still further object of the present invention to provide a novel and improved high gain dual antenna amplifier having a plurality of helical coil pulse modulated wave tubes connected in cascade wherein the time interval between the time that the coil of one tube is energized and the time the coil of the next tube is energized is equal to the time delay of passage of the signal through said one tube.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

FIG. 1 is a schematic diagram of a preferred embodiment of the present invention; and

FIG. 2 shows the idealized wave forms for pulsing the traveling wave tubes of the circuit of FIG. 1.

One preferred embodiment of the present inventon is illustrated in FIG. 1 of the drawing. As shown therein, traveling wave tubes 3, 4 and 5 are connected in cascade in a circuit that extends from the input antenna 6 through conductor 7 to probe 8, through the waveguide portion of tube 3 to probe 9, through conductor 10 to probe 11, through the waveguide portion of tube 4 to probe 12, through conductor 13 to probe 14, through the waveguide portion of tube 5 to probe 15, and through conductor 16 to the output antenna 17. The plate circuit of tube 3 extends from the positive high voltage supply line 18 through conductor 19 and the tube to its cathode and through resistor 19a to ground. The focusing coil 20 is disposed about the neck of tube 3 as shown and is energized by a circuit that extends from the supply line 18 through potentiometer 21 and the coil to ground. The control grid of tube 3 is connected to the center-tap of potentiometer 22 which is disposed between the supply line 18 and ground. The helical coil 23 within tube 3 is energized by a circuit that extends from the supply line 18 through the modulater 24 and the coil to ground. The plate circuit of tube 4 extends from the supply line 18 through conductor 25 and the tube to its cathode and through resistor 25a to ground. Focusing coil 26 is disposed about the neck of tube 4 and is energized by a circuit that extends from the supply line 18 through potentiometer 27 and the coil to ground. The control grid of tube 4 is connected to the center-top of potentiometer 28 which is disposed between the supply line 18 and ground. The helical coil 29 within tube 4 is energized by a circuit that extends from the supply line 18 through modulator 24, and through the delay line 30 and the coil to ground. The plate circuit of tube 5 extends from the supply line 18 through conductor 31 and the tube to its cathode and through resistor 31a to ground. Focusing coil 32 is disposed about the neck of tube 5 and is energized by a circuit that extends from the supply line 18 through potentiometer 33 and the coil to ground. The control grid of tube 5 is connected to the center-top of potentiometer 34 which is disposed between the supply line 18 and ground. The helical coil 35 within tube 5 is energized by a circuit that extends from the supply line 18 through the modulator 24, through delay lines 30 and 36 and through the coil to ground.

Inasmuch as the modulator 24 and the delay line networks 30 and 36 may take a great variety of different forms, a full description of the same is not included here for the sake of simplicity. For a complete understanding of the present invention it need only be understood that each delay line introduces a delay To in the output signal from the modulator, where To is about 0.2 microseconds and is the time required for a wave to travel from the input probe to the output probe of each tube, and that the modulator 24 continuously delivers a positive high voltage pulse to the helical coil of each tube for an interval of 2T0 and then opens up its energizing circuit for an interval of 3T0.

In operation, the incoming continuous wave radio frequency signal is picked up on the input antenna 6 and is transmitted down the length of tube 3 in the form of a wave. As is known in the traveling wave tube art, no amplification of the wave occurs until the velocity of the wave through the tube is reduced to approximately the velocity of the electron beam between the cathode and the anode of the tube. This is accomplished when the circuit between the high'voltage supply line 18 and the helical coil 23 is completed through modulator 24. As shown in FIG. 2 of the drawing when the high voltage pulse 37 is applied to the coil 23 for the 2T0 interval, no signal appears at the output probe 9 for a time To until the wave travels the length of the tube. When pulse 37 terminates, the amplification process ceases immediately so that the output pulse 38 from tube 3 occurs for an interval To. By the time the leading edge of pulse 38 reaches tube 4 the pulse 33 from modulator 24 has traversed delay line network 30. The output pulse 40 of tube 4 is therefore further amplified and delayed another interval of To as it travels the length of tube 4. Similarly by the time the leading edge of pulse 40 reaches tube 5, the pulse 41 from modulator 24 has traversed delay line networks 30 and 36. The output pulse 42 of tube 5 is therefore still further amplified and is delayed still another interval of To as it travels the length of tube 5.

It will be noted in FIG. 2 of the drawing that, even if the amplified output from the third traveling wave tube 5 is coupled back into the first traveling wave tube 3, no harmful self oscillation can occur since tube 3 is gated off when the output pulse 42 of tube 5 occurs.

Similarly, if the output of any tube in the circuit is fed back to the input of any other tube, no self oscillaton can occur since all said other tubes are gated off when the output of any said tube is energized.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

l. A pulsed repeater amplifier circuit comprising three traveling wave tubes, each said tube having a helical coil disposed therewithin; an input antenna; an output antenna; means connecting .the said antennas and the said tubes in cascade so that a wave received on the input antenna is conducted successively through the saidthree tubes to the output antenna; means for directing an electron beam of predetermined amplitude along the axis of the helical coil of each tube; and

means responsive to an individual periodic high voltage energization cycle for each coil for amplifying the wave during separate intervals as it travels through each tube.

2. The circuit as described in claim 1 wherein the am plifier means includes a high voltage source, a modulator, means connecting the modulator in series with the source and the coil of the first tube, a first delay line, means connecting the modulator in series with the source, the first delay line and the coil of the second tube, a second delay line, and means connecting the modulator in series with the source, the first delay line, the second delay line, and the coil of the third tube.

3. The circuit as described in claim 2 wherein the circuit through the modulator is completed for an interval of 2T0 and then opens for an interval of 3T0, where To is time required for the electron beam to travel the length of each said tube. 

1. A pulsed repeater amplifier circuit comprising three traveling wave tubes, each said tube having a helical coil disposed therewithin; an input antenna; an output antenna; means connecting the said antennas and the said tubes in cascade so that a wave received on the input antenna is conducted successively through the said three tubes to the output antenna; means for directing an electron beam of predetermined amplitude along the axis of the helical coil of each tube; and means responsive to an individual periodic high voltage energization cycle for each coil for amplifying the wave during separate intervals as it travels through each tube.
 2. The circuit as described in claim 1 wherein the amplifier means includes a high voltage source, a modulator, means connecting the modulator in series with the source and the coil of the first tube, a first delay line, means connecting the modulator in series with the source, the first delay line and the coil of the second tube, a second delay line, and means connecting the modulator in series with the source, the first delay line, the second delay line, and the coil of the third tube.
 3. The circuit as described in claim 2 wherein the circuit through the modulator is completed for an interval of 2To and then opens for an interval of 3To, where To is time required for the electron beam to travel the length of each said tube. 